IP Subnet Calculator
Calculate network, broadcast, usable hosts, wildcard mask, IP class and IPv4-mapped IPv6 for any IP address and CIDR prefix.
Network
192.168.1.0
Broadcast
192.168.1.255
First host
192.168.1.1
Last host
192.168.1.254
Usable hosts
254
Subnet mask
255.255.255.0
Wildcard mask
0.0.0.255
Total addresses
256
IP class
Class C
Visibility
Private
IPv4-mapped IPv6
::ffff:c0a8:125
Reverse DNS
37.1.168.192.in-addr.arpa
CIDR notation — /24 gives 254 usable hosts, /30 gives 2 (point-to-point links), /31 and /32 have no usable hosts.
How it works
Mask = leading 32−prefix bits set. Network = IP AND mask. Broadcast = network OR ~mask. Usable hosts = 2^(32−prefix) − 2.
Example: 192.168.1.37/24 → network .0, broadcast .255, 254 hosts.
Last updated: June 2026
How this calculator is verified
Checked by Rahim Virani on
- Network, broadcast and usable-host ranges derived from the CIDR prefix
- IPv4 octet input validated for 0-255 with leading-zero handling
- Subnet count and host count reconciled with the total address space
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Subnet planning is part of everyday network administration in India — setting up a small office LAN, segmenting a guest Wi-Fi, or allocating IPs for CCTV cameras in a building. This calculator takes an IP address and CIDR prefix and returns the subnet mask, network address, broadcast address and usable host range, so engineers can plan static IPs and DHCP scopes without overlaps. It is equally useful for ISP field technicians assigning blocks to residential connections, for students preparing for networking certifications, and for cloud engineers choosing VPC CIDR ranges that leave room to grow. A /26 gives 62 usable hosts, a /30 suits point-to-point links, and seeing the numbers prevents the classic mistake of allocating the network or broadcast address to a device.
How to Use This Calculator
- Step 1: Enter the IP address in the address field, such as 192.168.1.0.
- Step 2: Enter the CIDR prefix, the number after the slash, such as 26 for a /26 subnet.
- Step 3: Read the subnet mask, network address and broadcast address.
- Step 4: Note the usable host range — first host to last host — and the total usable host count for your plan.
Worked Example
Your office assigns the guest network 192.168.1.0/26. Enter the address and prefix, and the tool returns the subnet mask 255.255.255.192, the network address 192.168.1.0 and the broadcast address 192.168.1.63, with 62 usable host addresses. That range is what you can allocate to devices before running out. A /24 gives 254 usable addresses, while a /30 — common on point-to-point links between routers — allows only 2 usable addresses. Use the host range to plan static IPs and DHCP scopes without overlaps.
Tips and Common Mistakes
- •Tip 1: The usable count is always the total hosts minus two for the network and broadcast addresses, so a /26 yields 64 minus 2.
- •Tip 2: For point-to-point links between two routers, /30 or /31 is standard practice and wastes the least address space.
- •Tip 3: Keep the network address out of the DHCP range, since devices using the network address as their own IP will break connectivity.
- ✗Mistake 1: Typing a prefix larger than the address space allows — 192.168.1.0/32 addresses a single host and leaves no usable devices.
- ✗Mistake 2: Using the broadcast address as a device IP, which every router treats as a group address and will not route normally.
Frequently Asked Questions
What is a subnet mask?
It separates an IP address into the network part and the host part. 255.255.255.0 (/24) keeps the first 24 bits as network and gives 254 usable host addresses.
Why can't I use the first and last addresses?
The first address in a subnet is the network address and the last is the broadcast address — both are reserved and cannot be assigned to devices.
What is CIDR notation?
It writes the network size as a prefix — /24 means 24 bits of network. /24 gives 254 hosts, /30 gives 2 hosts (point-to-point links), /32 is a single address.
How do I choose the right subnet size?
Count your devices, double it for growth, and pick the smallest prefix that fits. A /29 supports 6 usable addresses, a /28 supports 14, and a /24 supports 254.